The present invention relates to an improved device for flushing a drain pipe of, for example, a kitchen sink, wash tub or other receptacle, which has become blocked or restricted by foreign material.
It is well known that drain pipes of sinks, wash tubs and other similar receptacles tend to become blocked or restricted by waste material. This generally arises due to the accumulation of waste material in the waste trap or "S-bend" in the drain pipe. One way of reducing the amount of solid matter passing down the drain pipe is to provide a perforated strainer in the mouth of the drain pipe, but such strainers do not prevent passage of relatively finely divided waste substances such as small pieces of vegetable matter and other waste material. Accordingly, it is necessary periodically to flush away waste material which is causing blockage or restriction in the drain pipe, particularly when the rate of drainage of water from the receptacle becomes unacceptably low.
Numerous flushing devices have been proposed in the past. The ancient U.S. Pat. No. 532,376 to Hoyt discloses such a device in which a plate is clamped to a sink strainer by means of L-shaped rods. These rods are provided with threaded portions and are urged against the underside of the sink strainer by thumb nut screws mounted on the threaded portions.
U.S. Pat. No. 1,173,854 to Pearch discloses a drain pipe flushing device having an inverted dish-shaped casing formed of cast iron and provided with a nozzle which is connected to a source of water. The casing is clamped into position over the sink strainer by means of thumb nuts mounted on L-shaped threaded rods in a manner similar to that described above in connection with the Hoyt patent.
U.S. Pat. No. 1,013,175 to Jones discloses a further type of sink flush device utilizing an L-shaped, threaded rod which hooks onto the sink strainer to effect clamping of the device over the mouth of the drain pipe. The device differs from the two prior devices described above in that it utilizes only one L-shaped threaded rod which is centrally disposed internally of the device.
U.S. Pat. No. 2,024,873 to Perry discloses another type of sink flush device employing an L-shaped member to secure the device in position. The L-shaped rod in the Perry patent extends through a conical-shaped sealing member which fits into the plug hole of the sink and the L-shaped rod is urged against the underside of the sink strainer by means of a coil spring.
U.S. Pat. Nos. 550,914 to Hoyt, 608,207 to Merritt, 1,395,125 to Lewis et al., 1,985,813 to Baden, 2,055,801 to Perry, 2,215,360 to Lundstrom and 2,570,546 to Hamlett all disclose flushing devices having a centrally disposed L-shaped or hook means which is urged against the underside of a sink strainer or similar anchoring means to effect clamping of the device over the mouth of the drain pipe. U.S. Pat. No. 2,529,587 to Bates et al. shows a device having a centrally disposed T-shaped member having particular applicability to the flushing of toilet bowls and bidets.
U.S. Pat. Nos. 2,061,553 to Acosta and 2,197,716 to Whitaker both disclose devices which have hook-shaped members positioned diametrically opposite each other and facing in opposite directions. These devices require the presence of a particular type of grid in the mouth of the drain pipe to allow entry of the hooks followed by rotation of the device to lock it into position.
None of the prior devices discussed above has proved entirely satisfactory. The major problems which are encountered with these devices are first they are usually very awkward to install, especially those which utilize an L-shaped hook member. Second, these devices do not provide a satisfactory seal over the drain pipe for the optimum pressures of water which are required to effectively flush the drain pipe. Third, these devices are generally cumbersome to handle and expensive to produce. As described below, the first problem referred to is particularly marked with those devices which employ more than one L-shaped hook member.
In most sinks and tubs, the strainer is supported in the mouth of the drain pipe on a ledge formed with detents, and is removable to facilitate access to the drain pipe. Occasionally, however, it is found that the strainer is permanently mounted in the mouth of the drain pipe, particularly in older domestic sink installations. Irrespective of whether the strainer is removable or not, it is necessary, when using one of the prior devices, first to align the L-shaped members so that they can be passed through the detents, or through the perforations in the strainer if not removed, prior to clamping the device over the drain pipe. When the thumb nut screws are turned, there is a tendency for the L-shaped members to rotate before they come into contact with the strainer support or the strainer plate, and they often disengage therefrom. It is, therefore, necessary with these prior device to employ both hands when tightening one thumb nut, one hand being required to hold the L-shaped member to prevent it turning and disengaging from the strainer support or strainer plate, while the other hand turns the thumb nut screw to effect tightening. Installation of such devices, therefore, is awkward, time-consuming and frustrating. In view of these disadvantages, devices of the type described above, especially of those disclosed in the Pearch and Hoyt patents, have not found wide acceptance domestically or industrially. In view of the unavailability of a sink flush device which can be easily and quickly installed to give a satisfactory seal and which can be produced at relatively low cost, unblocking of drain pipes is commonly achieved either by feeding a plumber's "snake" through the pipe to dislodge the foreign material which is awkward and inconvenient, or by using a conventional sink plunger which is also awkward to use and, ultimately, does not result in a satisfactory flushing of the drain pipe system.